The present invention relates to a video security system particularly, although not exclusively, envisaged for use in the monitoring of a plurality of locations, such as, in a building, for example, a casino.
More particularly the present invention relates to a video security system (VSS) particularly directed at addressing the difficulties which prior art security systems generally experience, such as:
1. avoiding text information obliterating important video information;
2. switching repeatedly between two or more views of interest with a single camera;
3. dealing with equalisation problems between video cameras, video monitors and/or VCRs or other video signal recording device;
4. overcoming the problem of tracking an object with a camera when it approaches a 360xc2x0 end stop;
5. overcoming the problem of pan/tilt camera control when zoomed out;
6. controlling the camera to move rapidly between two or more views of interest; and,
7. VCR management issues including: failure of VCRs; change-over delay in VCR cassettes; and dealing with camera failure and replacement.
It is to be kept in mind that the purpose of the video security system of the present invention is to provide video images regarding events pertaining to the security of a building or the like and to allow those recorded video images to be presentable in a court of law as irrefutable evidence of the events which took place.
Hereinafter the term xe2x80x9cVCRxe2x80x9d ill be used to denote any form of video signal recording and/or playback device (referred to as a xe2x80x9cVRDxe2x80x9d) and may include a video cassette recorder, or any optical or digital recording media suitable for recording video signals.
1. xe2x80x9cTest Overlayxe2x80x9dxe2x80x94In the field of video security systems it is known to introduce text into the video signal to provide a real time record of the details of the event which is being monitored. A disadvantage of such prior art systems is that the information is introduced into the video part of the video signal and hence over-writes a part of the video picture which would have otherwise been recorded.
The present invention overcomes this by inserting the text into the non-video part of the video signal.
2. xe2x80x9cTogglexe2x80x9dxe2x80x94The secret to the success of switching between a plurality of fixed locations is to be able to quickly and easily identify two, or more, viewing locations xe2x80x9con the flyxe2x80x9d. This is particularly for viewing targets of short term or temporary interest.
In the context of the present invention xe2x80x9con the flyxe2x80x9d means to be performed whilst the VSS is in its normal mode of operation and without interrupting the normal operation of the VSS.
Also, in the context of the present invention the feature of xe2x80x9cswitching back and forth between two (or more) viewing locationsxe2x80x9d is referred to as xe2x80x9ctogglingxe2x80x9d between the viewing locations.
However, where the operator is interested in two or more specific locations within the viewing region the PTZ camera must be adjusted manually between these locations. This is quite laborious and tedious for the person operating the PTZ camera since it involves adjusting the pan, tilt, zoom and focus setting for the PTZ camera.
We have discovered that this can be overcome by recording the PTZ camera settings corresponding to the desired locations of viewing into a camera position controller and switching between the locations by recalling the settings for each of the viewing locations. The PTZ camera then is controlled by the camera position controller to adjust itself between the desired locations.
xe2x80x9cPresetxe2x80x9d PTZ camera viewing locations are known and are widely used, however, they require the operator to make several control operations to set each viewing location and at least two control operations to switch from one viewing location to another.
This is particularly inconvenient in a viewing region such as in a casino where there are many potential targets, where there is a requirement to quickly and reliably set viewing locations and where it is critical to be able to switch between typically two targets. The two targets would typically be a suspected felon and a handbag which it is suspected that the felon will steal. Typically, there is an accomplice to be monitored as well. Usually the accomplice in this scenario is a woman who collides briefly with the felon and takes the handbag once the handbag has been stolen. Hence, the task of the operator of the VSS is to first monitor the suspected felon and the handbag by toggling back and forth between the two and once the handbag has been stolen to monitor the felon and then to monitor a person who may collide with the felon.
In the present invention we have determined a way to enable the operator to operate a single control function (such as by a control button) to set, update and toggle between two or more viewing locations. This most reliably and efficiently allows the operator to monitor the targets.
3. xe2x80x9cSignal Equalisationxe2x80x9dxe2x80x94Prior art video security systems have the problem that equalisation of the video signals must be provided for each video camera. That is, there must be one equalisation unit for each camera.
We have overcome this difficulty by having one equalisation unit for each video monitor and automatically adjusting the equalisation unit for each video camera as it is connected to the monitor. Hence, only a fraction of the number of equalisation units is required.
4. xe2x80x9cRotation End Stopsxe2x80x9dxe2x80x94Another problem of existing video security systems is that most of the cameras which they use are only able to rotate through about 360xc2x0. Hence, when following a target the camera can reach its end stops and have to unwind before it can continue to follow the target. By the time that the camera has unwound the target may no longer be in sight.
We have overcome this problem in an inexpensive way by using a cable loop wound in a way that is able to twist 3 to 4 times, and hence the camera can be rotated through an angle of about 1000xc2x0. A control unit of the camera then is programmed to return the camera to about the centre of its rotation when the camera is not being used to track a target. Hence, the camera is relatively unlikely to reach its end stops during normal use.
5. xe2x80x9cPan Speed vs Zoomxe2x80x9dxe2x80x94Prior art vide cameras have the further problem that when the lens is zoomed in (that is viewing an object at a distance) the rate of pan per degree of arc is the same as when the lens is zoomed out. Hence, it becomes difficult to accurately control the pan of the lens when zoomed in. Also, it is difficult to observe the image of the camera during panning when zoomed in because it is usually blurred or indistinct due to the pan speed being too high.
We have overcome this problem by linking the pan speed to the zoom position of the lens so that the rate of pan per degree of arc decreases as the lens is zoomed in and increased as the lens is zoomed out.
6. xe2x80x9cAccuracy of Camera Positioningxe2x80x9dxe2x80x94Conventional camera position controllers have problems in maintaining accuracy of positioning of the video camera (for viewing a target in a predetermined location) whilst seeking maximum speed of movement of the video camera. That is, in the race for maximum speed, so that one camera can be used to monitor two or more locations, the position controller is not able to keep accurate record of the location of the camera. This is primarily due to problems encountered in rapid changes in acceleration.
We have overcome this problem by designing a camera position controller which ensures that there is a minimum period of substantially zero acceleration before any change in acceleration direction. This thus avoids large changes in momentum introduced when switching abruptly from acceleration to deceleration.
7. xe2x80x9cNon-Recording Timexe2x80x9dxe2x80x94Another problem of prior art video security systems is that during the times referred to in item 7 of the Field of the Invention no recording can occur. Hence, the video security system can not record all events which its cameras see. For example, in a video security system having 125 VCRs there would be a minimum recording time loss of 2 hours per day due only to the time taken to change over tapes (assuming the operation takes 30 seconds and each tape records for 8 hours). There is further loss of recording when an operator deliberately takes a VCR off-line in order to review one of the tapes.
In order to overcome these periods of lost recording we have designed a VSS to automatically manage the VCRs and cameras so as to ensure that each target is monitored continuously and each video signal is recorded continuously. This is achieved by using backup video cameras and backup VCRs and by providing a log of the camera and VCR associated with each viewed target.
Therefore it is an object of the present invention to provide a video security system to overcome the above identified problems.
1. It is an object of the present invention to provide a text insertion system which enables storage of text other than in the part of the video signal which corresponds to the video image.
In accordance with another aspect of the present invention there is provided a text insertion system for a video security system having a video camera and a video monitor and/or a VRD capable of operation in a record mode, the text insertion system comprising:
a text insertion means connected between the video camera and the video monitor and/or VRD for inserting a text signal into a video signal received from the video camera for display on the video monitor and/or recordal by the VRD, the insertion of the text signal being timed within the back porch of the video signal so that the text signal does not alter the visible part of the video frame of the video signal;
a control means connected to the text insertion means, the control means generating the text signal and sending the text signal to the text insertion means; and,
a playback means operatively associated with the text insertion means and the control means, the playback means responding to the text signal portion of the video signal, the playback means having a text signal display means for rendering the text signal visible on the video monitor, and a text signal hiding means for rendering the text signal non-visible on the video monitor, and text signal display means and the text signal hiding means being operable by a person using the text insertion system to allow alternating between showing text corresponding to the text signal on the video monitor and showing on the video monitor that part of the video frame which would otherwise be obscured by the text, and the playback means being able to make the text signal visible or hidden during both recording and playback modes of operation of the VRD.
2. Therefore, it is an object of the present invention to provide a PTZ camera for a video security system which is capable of being controlled by an operator to toggle between a plurality of desired camera viewing locations.
In accordance with one aspect of the present invention there is provided a PTZ camera for viewing a plurality of targets within a region surrounding the PTZ camera, the PTZ camera comprising:
a video lens and camera for viewing the targets and sending a video signal to a video monitor and/or a VRD;
a zoom control means for controlling the video lens for viewing the targets;
a focus control means for focusing the video lens for viewing the targets;
a pan control means for panning the video lens and camera for viewing the targets;
a tilt control means for tilting the video lens and camera for viewing the targets; and,
a camera position control means for controlling the video lens, the zoom control means, the focus control means, the pan control means and the tilt control means, the camera position control means having a first current position means for storing the settings corresponding to the location of one of the targets, and a second current position means for storing the settings corresponding to the location of another one of the targets, the camera position control means being operable to switch control between the first current position means and the second current position means for allowing viewing to switch between two targets of present interest, wherein the first current position means and the second current position means are operatable to set, update and toggle the view on the video monitor between the two locations of the targets.
3. It is an object of the present invention to provide a transmission cable equalisation system for a video security system having a plurality of video cameras and a video monitor and/or a VRD capable of operation in a record mode, the transmission cable equalisation system comprising:
a selector means connected between the video cameras and the video monitor and/or VRD for selecting video signals from the video cameras to be directed to the video monitor and/or VRD so that the video signal from one video camera is display on the video monitor and/or recorded on the VRD at a time;
an equaliser means connected between the selector means and the video monitor and/or VRD for equalising the video signal from losses caused by the nature of the connection between each of the video cameras and the selector means; and,
a control means connected to the equaliser means and the selector means, the control means having a reference means having data quantifying the losses between each video camera and the selector means, and the control means controlling the equaliser means to compensate for the losses associated with each video camera as its video signal is displayed on the video monitor and/or recorded on the VRD so that the condition of the video signal at the video monitor and/or VRD is equalised substantially independent of the characteristics of the connection between the video camera and the selector means so that only one equalisation means is required per video monitor and/or VRD instead of one equalisation means per video camera.
4. It is an object of the present invention to provide a video camera which is controllable to rotate through a fixed angle which is greater than 360xc2x0.
In accordance with a still further aspect of the present invention there is provided a video camera for a video security system, the video camera comprising:
a video lens for viewing a target and sending a video signal to a video monitor and/or a VRD;
a transport mechanism upon which the video lens is mounted, the transport mechanism being rotatable through a fixed azimuth range of greater than 360xc2x0 so that the video lens can view targets which move through an azimuth range of greater than 360xc2x0; and,
a loop of electrical cables arranged to be able to twist through an azimuth range of greater than 360xc2x0.
5. It is an object of the present invention to provide a video camera which is controllable to pan at a speed which changes corresponding to the zoom setting of the camera.
In accordance with yet another aspect of the present invention there is provided a video camera comprising:
a video lens for viewing a target and sending a video signal to a video monitor and/or a VRD;
a zoom control means for controlling the video lens to see targets at varying ranges from the video camera;
a pan control means for panning the video lens; and,
a control means for controlling the speed at which the video lens is panned, the control means being able to set a relatively slow pan speed when the zoom control means controls the video lens to view a target which is relatively far from the video lens and to set a relatively high pan speed when the zoom control means controls the video lens to view a target which is relatively close to the video lens so that both distant and close targets can be panned over at substantially the same speed.
6. It is an object of the present invention to provide a camera transport mechanism which has a camera position control system for moving a camera rapidly between a plurality of viewing positions.
In accordance with a further aspect of the present invention there is provided a camera transport mechanism for moving a video camera between a plurality of viewing positions, the camera transport mechanism comprising:
a platform for carrying a video camera;
a vertical axis drive unit attached to the platform for moving platform about a vertical axis;
a horizontal axis drive unit attached to the platform for moving the platform about a horizontal axis; and,
a camera position control system for recording the location of a plurality of viewing positions and for controlling the movement of the platform between said viewing positions, the camera position control system being configured control the movement of the platform so as to provide a minimum period during which there is substantially zero acceleration between changes in acceleration of the platform from acceleration to deceleration so as to reduce the amount of rate of change of momentum experienced by the platform and thus improve the accuracy of determination of the position of the platform so as to more accurately control the movement of the platform and hence the video camera between the viewing positions.
7. It is an object of the present invention to provide a video camera substitution system for ensuring that video images are always available to be reviewed and/or recorded even in the event of the failure of a video.
In accordance with a still further aspect of the present invention there is provided a video camera substitution system for a video security system having a fixed video camera for viewing a target area, a pan-tilt video camera capable of orientation to substantially view the said target area and a video monitor and/or VCR capable of operation in a record mode, the video camera substitution system comprising:
a failure detection means for detecting failure of the fixed video camera;
a camera preset means having data concerning the position of the target area with respect to the pan-tilt video camera; and,
a control means in operative association with the failure detection means, the camera preset means and the pan-tilt video camera, the control means being capable of controlling the pan-tilt video camera for moving and setting the pan-tilt video camera to monitor the target area when the failure detection means detects failure of the fixed video camera so that the target area is monitored substantially continuously.
It is an object of the present invention to provide a video recorder substitution system for ensuring that video images and always recorded even in the event of the failure of a video recorder including failure to record due to change-over of recording media and taking the video recorder out of service.
In accordance with a still further aspect of the present invention there is provided a video recorder substitution system for a video security system comprising:
a first VRD for recording a video signal corresponding to a target area;
a second VRD also capable of recording the video signal corresponding to said target area;
a record failure detection means for detecting failure of the first VRD to record said video signal, including failure due to change-over of recording media and due to taking the video recorder out of record its mode of operation; and,
a control means in operative association with the record failure detection means, with the first VRD and with the second VRD, the control means being capable of controlling the second VRD to set the second VRD to record said video signal in the event that the record failure detection means detects failure of the first VRD so that the video signal corresponding to the target area is recorded substantially continuously.